5 stars: Pretty amazing resource. After about a month of use, the information from the morning reading has turned out to be really useful and surprising. Once you sort it into your training you'll be able to aim for high readiness on key event days, and know exactly when and why to back off. Knowing of tiredness is sympathetic or parasympathetic has been especially powerful.
5 stars: I have been using it for 10 months and found it very useful and reliable. Tracking all night sleep I realized my best resting level is not at waking up but 1 hour after having breakfast. Tracking HIIT sessions (walk up and down a small hill for half an hour) was also very interesting. After several weeks I identified clearly my HRmax, near 153 ppm (in agreement with 220-age formula). After several more months of HIIT I have read HRmax 164, more in agreement with 206-0.7xAge, and I feel in a really better fitness level. I never run in my life because lack of aerobic capacity, and now practise continuous jogging for more than 30 min at 120-140 ppm Really a very good App
4 stars: Been using for two months almost everyday: nice interface, sounds, readily understandable data readouts and analysis. I've used with a Polar H7 (very easy) and My Zone MZ-3 (very problematic) and the data definitely seem to be able to show my autonomic balance and how is effected by life events and decisions. I'm using it with clients with good results but I really wish the team data were more detailed....